TWI401111B - Purification process using microchannel devices - Google Patents

Description

Purification process using a microchannel device

The present application claims priority to U.S. Provisional Patent Application No. 60/961,370, filed on Jul. 20, 2007, and U.S. Provisional Patent Application No. 61,065,473, filed on Feb. 12, 2008. .

The present invention relates to a process for removing impurities from a compound having a relative volatility of equal to or less than 1.2 to form an ultrahigh purity compound.

There are still many unmet needs for ultra high purity compounds used as feeds, intermediates, solvents or final products for material processing and application. As used herein, ultra high purity is defined as a purity ranging from a lower limit of 10 to ¹⁰ % by weight (1 ppt) to an upper limit of 0.01% by weight (100 ppm). These compounds include, but are not limited to, distillable organics including monomers, solvents for chromatographic applications such as high performance liquid chromatography (HPLC), sublimable solids, electronic chemicals, and analytical reagents.

Conventional methods for purifying compounds include distillation, crystallization, extraction absorption, adduct purification, mass selective ultracentrifugation, and chemical treatment combined with distillation. These and other related methods (e.g., the distillation process disclosed in U.S. Patent Publication No. 2006/0016215 A1), because of the desired similar boiling or low relative volatility of the compound and impurities, as well as low impurity concentration and mass transfer (mass transfer) ) The driving force is therefore often limited. Compounds having a low relative volatility α (α = impurity vapor pressure / desired compound vapor pressure) equal to or less than 1.2 are particularly difficult to utilize by utilizing gas/liquid equilibrium The classification process is used for purification, thus making ultra-high purity materials impossible to obtain by conventional methods. Moreover, the purity that can be achieved using conventional methods is often economically limited. Unacceptable yield losses, input energy, or process cycle times due to impurities and physical and/or chemical properties of the compound can limit the purity available due to excessive capital costs and operating costs.

For example, the Fenske Equation can be used to estimate the minimum equilibrium level required for distillation based on the relative volatility (α) of the component and the desired purity. In order to remove the most problematic impurities with similar boiling points (α<1.2), the number of stages or theoretical plate equivalent height (HETP) may exceed 50, 100, or even 200, using the most advanced fillers currently available (HETP=0.05 to 0.20) m) It may also require a tower height of >10 meters. Towers of this size can be challenged by a large number of compounds for many applications, posing challenges and safety challenges and safety concerns.

Thus, there remains a need for a more cost effective process for purifying compounds containing impurities having a relative volatility of 1.2 or less.

The present invention meets the aforementioned needs by presenting the advantages of combining microchannel devices with known purification techniques. Microchannel devices provide better control of process conditions, increased safety, and speed to market from laboratory development to commercial production. These devices are extremely useful for purifying reagents, solvents, intermediates or end products. The observed advantages provided by microchannel technology are based on the small size and high surface area that can be formed in the device to enable high exchange rates between phases. Typically, microchannel structure sizes from 1 to 1000 microns are important by enhancing capillary and interface phenomena, and reducing heat transfer and The distance of mass transfer is used to improve the purification effect. The excellent heat transfer and mass transfer in these devices provides a high exchange rate between phases, as well as better temperature control for more efficient purification stages, or a smaller theoretical plate height (HETP), which allows for fixation More stages are provided in the purification device geometry to achieve higher purity. Furthermore, since the better integration of heat exchange increases energy efficiency, it has the advantage of reducing capital intensity and reducing operating costs. The microchannel device can further amplify the production without any loss of performance by "encoding the number of channels" or repeating a single channel only a plurality of times without having to increase the size of the reactor vessel by increasing the ratio. Moreover, in the case of traditional process amplification studies, the market demand can be met in a manner that saves time and cost.

The present invention provides a method of preparing an ultrahigh purity compound, comprising: separating at least one impurity compound from at least one target compound in at least one microchannel device; wherein the at least one target compound and the at least one impurity compound have equal to or less than The relative volatility of 1.2; further wherein the at least one target compound has a result purity of 99.99%.

As used herein, a "microchannel device" is meant to have a three-dimensional structure (fluid flow channel or space) that is typically 0.1 to 5,000 microns, more specifically between 10 and 1,000 microns, perpendicular to the flow. Structured devices (usually the above devices, but other microstructured devices are not excluded).

The microchannel device of the present invention has a variety of fabrication techniques and structural materials. Several structural materials include, but are not limited to, metals, polymers, tantalum, ceramics, and glass. Table 1 below illustrates several manufacturing techniques available for various microchannel devices:

The microchannel device of the present invention may optionally contain a wick structure. The capillary structure helps to increase the interfacial exchange area and maintains the liquid phase and vapor phase in the unconnected regions of the device, minimizing reverse mixing of reduced performance. The capillary structure can be of any type currently known to those skilled in the art. The microchannel device of the present invention can have HETP ranging from less than 5 cm to less than 0.25 cm. In some cases, the microchannel device has a HETP of less than 0.05 cm.

The microchannel device described above is useful because it increases heat transfer and mass transfer. Heat transfer and mass transfer are enhanced by the structure or manner that constitutes the microchannel device and operates. Smooth channel walls help improve heat transfer and quality. Other structural features on the channel walls, such as grooves, textures, and graphics, also contribute to improved heat transfer and mass transfer of the device, making the device more efficient. Contains at least one Any substance of the target compound and at least one impurity compound (having a relative volatility of equal to or less than 1.2) can be separated by feeding the sample material through a microchannel device. As used herein, a "target compound" is any compound that can be attempted to give a predetermined purity after purification. As used herein, "impurity compound" means any substance that is desired to be separated from a target compound in combination with a target compound. In the present invention, at least one target compound will be separated from at least one impurity. It is an object of the present invention to separate at least one impurity compound from at least one target compound such that the resulting target compound has a purity of at least 99.9999%, at least 99.999%, or at least 99.99%. Microchannel devices can be used alone or in combination with other known purification techniques to achieve this purity.

The microchannel device can be used alone or in combination with other known purification techniques. One type of technique is, for example, adsorption purification or chemical purification in which the adduct is purified by temperature swing adsorption. A selective adsorbent, or a Lewis base, such as an amine, phosphine or ether, which forms an adduct, can be supported on the surface of the microchannel to provide an extremely high exchange area in contact with the impurity-containing stream. Other microchannels allow the heat transfer fluid to flow to achieve precise temperature control of the device while effectively regulating and cycling between the adsorption and desorption steps. The microchannel device can be used in conjunction with, for example, a chemical purification process using an ionic liquid as a purifying agent. For the sake of explanation, the organometallic compound is purified by mixing an organometallic compound containing an impurity with an ionic liquid, heating the resulting mixture, and then separating and separating the ultrapure organometallic compound. This method can be used in conjunction with microchannel devices to substantially reduce metallic, organic, and organometallic impurities present in the target organometallic compound. This combination method can get the ratio Those obtained by conventional purification processes have less organometallic compounds containing noisy qualities to meet the stringent purity standards required by the semiconductor industry (all impurities <10 ppb).

Ionic liquids are generally liquids that are liquid at low temperatures and have a melting point below 100 °C. Many ionic liquids are still liquid at room temperature and are therefore referred to as room temperature ionic liquids. The ionic liquid system consists entirely of ions, typically consisting of a large number of organic cations and inorganic anions. Due to the high Coulomb force in these compounds, the ionic liquid does not actually have a vapor pressure.

Any suitable ionic liquid can be used in the present invention. Exemplary cations for use in ionic liquids include, but are not limited to, hydrocarbyl ammonium cations, hydrocarbyl phosphonium cations, hydrocarbyl pyridinium cations, and dihydrocarbylimidazolium cations, respectively, as set forth in Types I-IV below. Exemplary anions useful in the ionic liquids of the present invention include, but are not limited to, chlorometalate anions; fluoroborate anions such as tetrafluoroborate anions and hydrocarbyl-substituted fluoroborate anions; and fluorophosphate anions such as hexafluoro a phosphate anion; a fluorophosphate anion substituted with a hydrocarbyl group. Examples of chlorometalate anions include, but are not limited to, chloroaluminate anions such as tetrachloroaluminate anion and chlorotrialkylaluminate anion; chlorogallate anions such as chlorotrimethylgallate anion and tetrachlorogallate anion And a chloroborate anion such as a tetrachloroinlate anion and a chlorotrimethylinthate anion.

In the above formula I-IV, R = H, (C _l - C ₁₀ ) alkyl, such as methyl, ethyl, propyl, butyl, pentyl, hexyl and octyl; aralkyl, For example, benzyl; alkenyl, such as allyl; aryl, such as phenyl; or di(C ₁ -C ₆ )alkylamino (C ₁ -C ₁₀ )alkyl, such as dimethylaminomethyl , dimethylaminoethyl, dimethylaminopropyl and diethylaminopropyl; and X is a halide such as a chloride. Each R group can be the same or different.

Other purification processes based on microchannel device technology, such as distillation, stripping, extraction, and adsorption systems, provide enhanced heat transfer and mass transfer required to achieve ultra high purity products (ppm, ppb, ppt). In addition, these purification processes provide the transport level enhancement required to address the problem of purifying a fluid mixture having a similar boiling point (relative volatility, 0.8 < α < 1.2) to high purity. Advantageous operating conditions include the ability to cause one or more fluid components in the liquid phase to change to a vapor state via a phase change, or to a temperature and pressure in an adsorbed state on the adsorbent. This operating condition may include a temperature of -25 ° C to 250 ° C and a pressure of 0.1 pa to 10 MPa. The feed impurity amount can range from 1 ppm up to 10% by weight of the fluid mixture or even 50% by weight.

Microchannel devices can be used to purify various compounds. The impurities of the compounds of the present invention typically have a relative volatility of less than 1.5 and are therefore difficult to purify by conventional distillation methods. More preferably, the relative volatility of the impurities in the compound includes alpha 1.2. Distillable organics (e.g., monomers, etc.) can be used to synthesize polymers that require ultra high purity to achieve high value applications for stringent product requirements in food, pharmaceutical or human health applications. These applications may include medical devices for drug delivery, human health diagnostics, human implantable devices, and ion exchange resins for purifying/manufacturing biological, pharmaceutical or nutraceutical compounds. One way to obtain ultra high purity polymer products is to reduce impurities in the starting monomers.

Other applications for high purity monomers include the manufacture of low volatile organic content (VOC) acrylic latex paints. In particular, when manufacturing a low VOC coating derived from butyl acrylate, it is necessary to remove impurities having similar boiling points in the monomer as a method of reducing residual VOCs in the final product. Low VOC coatings are characterized by a volatile impurity amount of 100 ppm or less. One of the particularly troublesome impurities with similar boiling points is dibutyl ether (bpt = 140 ° C), which has a boiling point close to that of butyl acrylate (bpt = 145 ° C) and a relative volatility of α = 1.20. Purification of butyl acrylate using current conventional distillation columns requires high capital investment and high operating costs. The method of the present invention enables a more pure product to be produced in a more efficient and cost effective manner.

Ultra high purity monomers are particularly useful in the manufacture of specialty polymers for applications including lithography and optoelectronics. In some cases, the optical isomer of a certain monomer must be removed to give the desired polymer properties.

Furthermore, the ultrahigh purity monomers and solvents used in the electronic materials may include various organic chemicals such as substituted acrylates and methacrylates, acetone, methyl tertiary butyl ether (MTBE). , propylene glycol monomethyl ether acetate (PGMEA), cyclohexanone and dimethylformamide (DMF). These ones Monomers and solvents are lithographic polymers and ancillary products used in the manufacture of wafers for integrated circuits. Computer chip manufacturers also use a variety of solvents, chelating agents, and cleaning solutions as cleaning residue removers to clean the twins during the manufacturing process. Ultra-high purity product specifications determine the use of high purity materials in all aspects of wafer processing.

The microchannel device can be further combined with one or more other purification processes to form a hybrid purification process that overcomes compositional or thermodynamic barriers to solubility or gas-liquid equilibrium, or that does not provide high purity products. These processes include, but are not limited to, extractive distillation, azeotropic distillation, extraction crystallization, membrane permeation/membrane distillation, reverse osmosis/reverse phase distillation, reactive distillation, catalytic distillation, stripping distillation, and other mixing known to those skilled in the art. Purification process.

In extractive distillation, the relative volatility of the feed components will vary due to the addition of a solvent or other addition stream that selectively interacts with at least one component to increase the relative volatility of at least one component and can be easier. Ground separation and purification. The choice of solvent will affect the recovery of the desired product into an overhead product or a bottoms product. The choice of solvent is determined by the nature of the compound to be purified, and may include, for example, water, organic hydrocarbons, and ionic liquids. The solvent to be added is typically recovered in a separate solvent recovery column and then recycled to the extractive distillation column. The microchannel device can be used in an extractive distillation column, a solvent recovery column, or both. The higher separation efficiency (lower HETP) provided by the microchannel device can help to overcome the limitation of the purity obtained by the higher cycle ratio, which lowers the concentration and efficiency of the extraction solvent in the conventional column.

In azeotropic distillation, a solvent is added to produce or change one or one The composition of the upper feed component is the pinch point. The azeotrope produced in the first column as a top or bottom product is sent to a second column where the desired purified stream is recovered as a concentrated product by the addition of a solvent to destroy the azeotrope. The mixed solvent/feed stream is further processed, the solvent is recovered and recycled to the second (azeotropic distillation) column, and by-products/impurities in the first column are removed.

In the extraction crystallization process, a solvent is added to change the relative solubility of two or more solute to affect the crystallization process. It may include a change in the constituent eutectic which prevents the formation of a pure phase, or a temperature-insensitive solubility curve which prevents the pure substance from being easily separated by adjusting the temperature. The solvent is recovered by distillation and recycled to affect the dissolution behavior. High efficiency microchannel distillation provides the only means of ensuring the presence of high purity solvents in the recycle, helping to increase the efficiency of the crystallization process and reduce the flow and cost associated with solvent flow.

In a mixed purification system for membrane and/or reverse osmosis distillation, a distillation column is coupled to a membrane separation unit to increase the efficiency of the purification process. In one embodiment, the feed stream can be first treated through a membrane to concentrate the feed stream and reduce the size of the downstream distillation column. In a second embodiment, the product of the distillation column can be passed to a membrane unit for a secondary purification or milling step.

Claims (9)

A method of preparing an ultra-high purity compound, comprising: separating at least one impurity compound from at least one target compound in at least one microchannel device; wherein the at least one target compound and the at least one impurity compound have a relative value less than or equal to 1.2 Volatility; the at least one microchannel device having a size between 0.0001 millimeters (mm) and less than 0.01 mm perpendicular to a flow of the at least one target compound and the at least one impurity compound; further wherein the at least one target The compound has a result purity of 99.99%. The method of claim 1, wherein the at least one microchannel device is a microchannel distillation device. The method of claim 1, wherein the purifying in the at least one microchannel device is performed by temperature swing adsorption. The method of claim 1, further comprising at least one microchannel device comprising a capillary structure. The method of claim 1, wherein the microchannel device has a theoretical plate equivalent height (HETP) of less than 5 cm. The method of claim 1, wherein the amount of the at least one impurity is reduced to less than 100 ppm of the total amount of the at least one target compound and the at least one impurity compound. The method of claim 1, wherein the at least one microchannel device is at least one other selected from the group consisting of distillation, stripping, extraction, and adsorption. The purification process is used in combination. The method of claim 1, wherein the target compound having a purity of 99.99% is used for electronic material applications. The method of claim 7, wherein the target compound having a purity of 99.99% is used for electronic material applications.